[GraphQL] Gracefully handle failed type assertions (#1650)

Signed-off-by: James Phillips <jamesdphillips@gmail.com>

backend/apid/graphql/environment.go

@@ -64,7 +64,6 @@ func (r *envImpl) Description(p graphql.ResolveParams) (string, error) {
 func (r *envImpl) ColourID(p graphql.ResolveParams) (schema.MutedColour, error) {
 	env := p.Source.(*types.Environment)
 	num := env.Name[0] % 7
-	logger.WithField("name", env.Name).WithField("num", num).Info("finding colour")
 	switch num {
 	case 0:
 		return schema.MutedColours.BLUE, nil
@@ -92,11 +91,12 @@ func (r *envImpl) Organization(p graphql.ResolveParams) (interface{}, error) {
 
 // Checks implements response to request for 'checks' field.
 func (r *envImpl) Checks(p schema.EnvironmentChecksFieldResolverParams) (interface{}, error) {
+	res := newOffsetContainer(p.Args.Offset, p.Args.Limit)
 	env := p.Source.(*types.Environment)
 	ctx := types.SetContextFromResource(p.Context, env)
 	records, err := r.checksCtrl.Query(ctx)
 	if err != nil {
-		return nil, err
+		return res, err
 	}
 
 	// apply filters
@@ -127,16 +127,14 @@ func (r *envImpl) Checks(p schema.EnvironmentChecksFieldResolverParams) (interfa
 
 	// paginate
 	l, h := clampSlice(p.Args.Offset, p.Args.Offset+p.Args.Limit, len(filteredChecks))
-	return newOffsetContainer(
-		filteredChecks[l:h],
-		len(filteredChecks),
-		p.Args.Offset,
-		p.Args.Limit,
-	), nil
+	res.Nodes = filteredChecks[l:h]
+	res.PageInfo.totalCount = len(filteredChecks)
+	return res, nil
 }
 
 // Silences implements response to request for 'silences' field.
 func (r *envImpl) Silences(p schema.EnvironmentSilencesFieldResolverParams) (interface{}, error) {
+	res := newOffsetContainer(p.Args.Offset, p.Args.Limit)
 	env := p.Source.(*types.Environment)
 
 	// finds all records
@@ -179,18 +177,15 @@ func (r *envImpl) Silences(p schema.EnvironmentSilencesFieldResolverParams) (int
 		sort.Sort(types.SortSilencedByID(filteredSilences))
 	}
 
-	// paginate
 	l, h := clampSlice(p.Args.Offset, p.Args.Offset+p.Args.Limit, len(filteredSilences))
-	return newOffsetContainer(
-		filteredSilences[l:h],
-		len(filteredSilences),
-		p.Args.Offset,
-		p.Args.Limit,
-	), nil
+	res.Nodes = filteredSilences[l:h]
+	res.PageInfo.totalCount = len(filteredSilences)
+	return res, nil
 }
 
 // Entities implements response to request for 'entities' field.
 func (r *envImpl) Entities(p schema.EnvironmentEntitiesFieldResolverParams) (interface{}, error) {
+	res := newOffsetContainer(p.Args.Offset, p.Args.Limit)
 	env := p.Source.(*types.Environment)
 	ctx := types.SetContextFromResource(p.Context, env)
 	records, err := r.entityCtrl.Query(ctx)
@@ -231,21 +226,19 @@ func (r *envImpl) Entities(p schema.EnvironmentEntitiesFieldResolverParams) (int
 
 	// paginate
 	l, h := clampSlice(p.Args.Offset, p.Args.Offset+p.Args.Limit, len(filteredEntities))
-	return newOffsetContainer(
-		filteredEntities[l:h],
-		len(filteredEntities),
-		p.Args.Offset,
-		p.Args.Limit,
-	), nil
+	res.Nodes = filteredEntities[l:h]
+	res.PageInfo.totalCount = len(filteredEntities)
+	return res, nil
 }
 
 // Events implements response to request for 'events' field.
 func (r *envImpl) Events(p schema.EnvironmentEventsFieldResolverParams) (interface{}, error) {
+	res := newOffsetContainer(p.Args.Offset, p.Args.Limit)
 	env := p.Source.(*types.Environment)
 	ctx := types.SetContextFromResource(p.Context, env)
 	records, err := r.eventQuerier.Query(ctx, "", "")
 	if err != nil {
-		return nil, err
+		return res, err
 	}
 
 	// apply filters
@@ -280,12 +273,9 @@ func (r *envImpl) Events(p schema.EnvironmentEventsFieldResolverParams) (interfa
 
 	// pagination
 	l, h := clampSlice(p.Args.Offset, p.Args.Offset+p.Args.Limit, len(filteredEvents))
-	return newOffsetContainer(
-		filteredEvents[l:h],
-		len(filteredEvents),
-		p.Args.Offset,
-		p.Args.Limit,
-	), nil
+	res.Nodes = filteredEvents[l:h]
+	res.PageInfo.totalCount = len(filteredEvents)
+	return res, nil
 }
 
 // CheckHistory implements response to request for 'checkHistory' field.

backend/apid/graphql/pagination.go

@@ -20,10 +20,9 @@ type offsetPageInfo struct {
 	totalCount int
 }
 
-func newOffsetContainer(nodes interface{}, totalCount, offset, limit int) offsetContainer {
+func newOffsetContainer(offset, limit int) offsetContainer {
 	container := offsetContainer{}
-	container.Nodes = nodes
-	container.PageInfo.totalCount = totalCount
+	container.Nodes = make([]interface{}, 0)
 	container.PageInfo.offset = offset
 	container.PageInfo.limit = limit
 	return container